America will decide for itself. One resident at a time. I am American, and I've decided in favor of contactless payment. So there will be me, and people like me, who sometimes go shopping without carrying cash or cards.
Eventually stores that don't accept contactless payment will notice when they start losing sales. It may take a decade or two for it to become ubiquitous--and that's perfectly okay.
What won't happen is an immediate changeover in a couple of decades. Some of us are ready now, and some are not ready yet, and we won't reach a tipping point unless it starts at some point, and starts to grow. Thankfully for me, it has already started (several years ago, and then a major entry by Apple into the space two years ago).
I think you'll start to notice it in a few years. You'll stop to buy gas, and find that if you want to dip or swipe your card (or pay cash!) you have to go inside to do it. To pay at the pump, you'll need some form of contactless payment.
